<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../react18/react.development.js"></script>
  <script src="../react18/react-dom.development.js"></script>
  <script src="../react18/babel.min.js"></script>
</head>

<body>
  <div id="app"></div>
  <script type="text/babel">

    class App extends React.Component{
      state = {
        count:0,
        isHot:true
      }

      render(){
        console.log("----render----");
        const {count,isHot} = this.state;
        return (
          <div>
            <button onClick={this.handle} >+</button>
            <p>{count}</p>

            <button onClick={this.changeWeaHandle}>切换天气</button>
            <p>{isHot?"热啊":"冷啊"}</p>
          </div>
        )
      }

      //事件函数
    //直接修改state不会重新调用render 不会重新渲染  错的  不能直接修改state
      handle = () => {
        let {count} = this.state;

        // 理解 没有直接修改state  拿到state的值用变量保存了
        // 先执行++1  再把值返回回去
        // this.setState({count:++count})


        // 理解  a++  a+1  不是一样的
        this.setState({count:count + 1})
      }

      changeWeaHandle = () => {
        const {isHot} = this.state;
        this.setState({isHot:!isHot})
      }
    }

    const root = ReactDOM.createRoot(document.getElementById('app'));
    root.render(<App/>)




  </script>
</body>

</html>